GB1290597A - - Google Patents

Abstract

1290597 Transistor amplifying and gating circuits; phase detectors; gain control SONY CORP 24 April 1970 [1 May 1969] 19817/70 Headings H3A H3T and H4R A transistor circuit comprises a pair of transistors Q1, Q2, having first, second and third electrodes, at least one of the first electrodes being supplied with an input signal, means for deriving an output signal from at least one of the second electrodes, and means, i.e. transistors X1, X2 connected with the third electrodes for producing a constant current. It is characterized in that a pair of diodes D1, D2 are provided to constitute a series connection between the third electrodes and that semi-conductor control means, i.e. transistor 1, is connected between the pair of diodes to give switching operation to the pair of diodes with a control signal. In the embodiment, signals are applied in opposite phase to the bases of both transistors Q1, Q2 and are taken from both collectors by means of load resistors R1, R2. Resistors r1, r2 are connected in series with diodes D1, D2, and a resistor 6 is common to the emitter circuits of transistors X1, X2. In a modification (Fig. 4, not shown) this resistor is replaced by the collector to emitter path of a further transistor (X3) and the transistor 1 is replaced by a pair of parallelconnected transistors (21, 22). The transistors Q1, Q2 may drive a further pair of transistors in long-tailed pair connection (Fig. 3, not shown). The arrangement may be used as a gating circuit, the gating signal being applied to the base of transistor 1, as an automatic gain control circuit, applying the a.g.c. voltage to the base of transistor 1 and the diodes D1, D2 acting as variable impedances, as a synchronous detector, or as a phase detector. It may alternatively use field-effect transistors.